Method of refining oils with &#34;versene&#34;



Patented May 12, 1953 METHOD OF REFINING OILS WITH VERSENE Edward M. James, Winchester, Mass, assignor to Lever Brothers Company, New York, N. Y., a

corporation of Maine No Drawing. Application August 9, 1950, Serial No. 178,546

9 Claims. (Cl. 2ti 0425) This: invention relates to the refining of vegetable and animal oils, and more particularly to a process of reducing losses experienced when said oils are treated with aqueous alkali solutions to separate free fatty acids therefrom.

The caustic alkali solutions conventionally employed to neutralizethe free fatty acids present in fatty glyceride stocks frequently through emulsification or occlusion carry ofi a portion of refined neutral oil, thereby occasioning considerable losses in large scale commercial processing.

Accordingly, it is an object of the present invention to achieve a reduction in the losses of glyceride oils and fats during alkali-refining.

It is a further object to provide a method of refining such fats and oils by either continuous alkali-refining processes or batch refining processes which is characterized by low refining losses.

These objects are accomplished by incorporating in the refining mixture a small amount of an organic amino-carboxylic acid compound having in relation to onebasic nitrogen atom more-than one carboxylic acid group standing in alpha position thereto. .This compound may be dissolved or dispersed in the oil or in the aqueous. alkali solution prior to blending, or it may be addedto the oil-aqueous alkali-refiningv mixtures Ethylenediaminetetraacetic acid is preferred and has the following formula:

noooom cmooon NCHz-CHN noooohz omooon It is available commercially in the form of the tetrasodiumsalt under the trade-mark 'Versene,.and may be employed as the acid or as an acidicor neutral salt. While this compound is preferred, any compound of the above-defined type may be employed, such as trimethylamine tricarboxylic acid, and alkyl and aryl iminodiacetic acids in the acid form or as an alkali metal salt such as the odium, potassium, ammonium or equivalent water-soluble acidic or neutral salt.

Compounds of this type have been found effective, whether employed in the wet or dry batchalkali-refining processes, or in a continuous refining process. Those processes are described in detail in the literature and form no part of the present invention. For convenience in understanding the invention, however, it may be stated that in batch refining a measured amount of oil with a quantity of aqueous alkali slightly inexcess of that required to fully neutralize the free" fatty acids contained therein are mixed in a kettle and heated. In the dry method the soap stock i allowed to settle at the bottom of the kettle and then recovered in a solid or semisolid form from the cooled oil. In the wet method a sprayof hot water is directed upon the surface of the oil, washing down the precipitated soap stock.

A continuous method to which the process of the invention is particularly applicable is the Sharples centrifugal process, In this process continuous streams of oil and aqueous alkali are fed and mixed at room temperature, i. e. F., then heated quickly to about F. to break the emulsion of oil and soap stock, and the soap stock and oil separated in high speed centrifuges. The refined oil may be washed once or twice with 10% of its own weight of water at to F'., and dried in a vacuum to remove occluded water. The process has been the subject of numerous patents describing variations. The

process is equally applicable to these variations.

It has been determined that as little as 0.075% of the additive is sufficient in many cases to markedly reduce refining losses. However, 11p to 1% can be employed with good results. Surprisingly, between 0.075 and 1% is the optimum range, amounts of additive below the range giving near-normal or even more than normal refining losses, and amounts above it giving no greater reduction therein.

The process of the invention is especially applicable to the alkali-refining of soybean oil, and. cottonseed oil. It may be used in the alkali-- refining of glyceride stocks composed of vegetable: and animal oils of all types, and mixtures thereof, such as corn oil, peanut oil, linseed oil, sesame oil and tung oil, to mention a few of the vegetable oils, and animal oils, such as sardine, herring or menhaden oils. The process is adapted to'the refining of either crude or degummed oils.-

Any alkali hydroxide may be employed, although sodium hydroxide is most generally used. Also, nonsaponifying alkalis, such as sodium carbonate, or trisodium phosphate, or mixtures thereof with saponifying alkalis may be used.

The maximum amount of alkali as NaOl-I to be used is calculated from the usual formula:

f. f. a. 5.2

Percent O.54=percent dry sodium hydroxide ferred to add the additive in the form of an aqueous solution thereof.

A preferred procedure is to mix an aqueous solution of tetrasodium salt of ethylenediaminetetraacetic acid with the oil, with the injection of 1% to 2%., steam before mixing with aqueous alkali.

The following examples are given in order to facilitate a clear understanding of the invention:

Example 1 A number of wet batch process refinings were made on expeller soy bean,oil cuntaining i60% free fatty acids using 6.7% (12 Bee).- aqueous: alkali solutions containing varying quantities of Versene (tetrasodium salt of ethylenediaminetetraacetic acid). These solutions were prepared; by adding sufficient 25% aqueous Versene solution to the aqueous alkali to bring the. Versene concentration (based onthe weight of the oil) "to the amountstated. The following results were Obtfiiflfid Percent. refining loss: Control (noVersene) 101 1%: Versene 2.8?- 0.5 Versene 3.8 041% 3.6

In. all. casesxthetsodium. hydroxide concentration. solutiollv Was. 6... 1% ,(125. B.)

The-facts was formed very rapidlyin .sandelikeparticles. which settled quickly, and on. settling. pacl: ed ..so ;tightly, that. a, minimum amount .of oil was, entrained therein. Wash. water applied. formeda clean layer. between the foots. and the oil being, unabll'a tofipenetrate the. tightly packed. ect smasan ontrast, the washwat r duri s a efinjng withilutjhe addition of Versene pene trated theioots attire bottomof the kettle. Very; clean separations. without emulsion. formationwere optained when .Versene was .used. as an d itive.

Ina run without additive the footswere light and .ficcculent. and-theioil retardedithesettling of the. fioc li particles, whereas in the .run. con-.- ami f ei r na he particles. w re spherical .-.in- MPQ-TFLBGL- ere-n t retarded by theaoil oncetheyt were rmed.

Example 2 Percent Refining Efliciency Percent Refining Loss Control;.... 0.05% Verse 0.075%,Versen 0.1% Versene;

1 'Iheneutraloil recovered divided by the neutral .oil in the un- Nondeeu medeso ean.-.=.0i o ta i 19.6%?

Percent Percent Refining Refining Loss Efliciency Control.(l%%stearn injected, no Versene) 4. 79 97. 80 Cold Mixing with 0.1% Versene 4. 50 98.05 Gold .Mixing with 0.125% Versene. 4. 49 98. 06 Cold Mixing with 0.075% ,Vcrsene" 4. 66 97. 89 1 4% Steam plus 0.125% Versene" 4. 29 98. 26 1%%. Steam Q1115. 0.1% Versene 4. 32 98. 23

Example 4 Nondegummed soy bean oil containing 0.55% free fatty aeidswas treated with aqueous alkali the presence of a-tetrasodium salt of ethylenediaminetetraacetic acid in aSharples continuous refiningprocess with 1 27 steam injection, as set forth in lilxample 2, with the following results:

Percent Percent Percent Refining Reduction Refining 1 Loss in Loss Efiiciency Control. 4. 20 97.55 0: 10% Versene 3.49 0.71 98.27 Do 3. -59 0; 61 98. 17

1 In this run the Versene was added to the blended mixture. 3 In this run the Versene was added to the aqueous alkali- Whilespecific examples of the invention have been given above, it is to :be understood that this" hasabeen done merely forpurposes ofillustration and that the true scope of the inventionis not :toxbe considered aszlimited thereby.

The? refined oil is substantially completely neutral and free of residual impurities, is of excellent quality and meets the color requirements ofirthe' art. The additives ofthe-invention have no. deleterious eiTects on the normal operation-of continuous. alkali-refining: processes.

Other 5 variations and modifications of the 111-" vention will be apparent to those skilled in the art,-

and-thexinvention contemplates all suchvariations and modifications which-come within the:

scope of the appended claims.

All amounts and percentages are on a weight basis unless otherwise indicated." Proportions of additive are 'by-weight of the crude'oil.

Iclaim:

1.. A-process of refiningla fatty glyceride stock which comprises treating the-stock with aqueous alkali-solution in an. amount atleast sufficient to neutralize free fatty acids contained in thestock in, the presence of not .over 1.0 of an organic amino-.carboxylic acid- -compound selected -fromthe group consisting of tetra alkali'metal salts-of ethylene diamine-tetraacetic acid, trialkali metal saltsiof trimethylamine tricarboxylic acid and di alkali metalsalts of alkyl and aryl iminodiacetic acidsato reducerefining losses, andthen separatingsoapstock from the refined oil.

2. -A process in accordancewith claim l whereinthesoapstock and refined oil are separated centrifugally.

3. @A process 'of claim 2 in which. the stock and alkali are continuously mixed. and --inwhich thecentrifugal separation is carried out continu 4. A--process'-of, claim -1 in which the so'apstock'" 6 and refined oil are formed into separate layers by 9. A process of claim 1 wherein the organic settling. amino-carboxylic acid compound is a trisodium 5. The process of claim 1 wherein the fatty salt of trimethylamine tricarboxylic acid.- glyceride is a soy bean oil.

6. A process of claim 1 wherein the organic 5 EDWARD M. JAMES. amino-carboxylic acid compound is the tetrasodium salt of ethylenediaminetetraacetic acid. n es i ed in h file f his pa en '7. The process Of claim 3 in Which the additive UNITED STATES PATENTS is mixed with oil before mixing with the alkali.

8. The process of claim 7 in which up to 2% of 0 steam is mixed with the oil before mixing with the alkali.

Number Name Date 2,463,015 Bersworth Mar. 1, 1949 

1. A PROCESS OF REFINING A FATTY GLYCERIDE STOCK WHICH COMPRISES TREATING THE STOCK WITH AQUEOUS ALKALI SOLUTION IN AN AMOUNT AT LEAST SUFFICIENT TO NEUTRALIZE FREE FATTY ACIDS CONTAINED IN THE STOCK IN THE PRESENCE OF NOT OVER 1.0% OF AN ORGANIC AMINO-CARBOXYLIC ACID COMPOUND SELECTED FROM THE GROUP CONSISTING OF TETRA ALKALI METAL SALTS OF ETHYLENE DIAMINE TETRAACETIC ACID, TRI ALKALI METAL SALTS OF TRIMETHYLAMINE TRICARBOXYLIC ACID AND DI ALKALI METAL SALTS OF ALKYL AND ARYL IMINODIACETIC ACIDS TO REDUCE REFINING LOOSES, AND THEN SEPARATING SOAPSTOCK FROM THE REFINED OIL. 